1. Field of the Invention
The present invention relates to a device testing apparatus and test method for testing IC chips and other electronic devices inside a chamber in a state of ordinary temperature or less (ordinary temperature or temperature lower than that), more particularly relates to a device testing apparatus and teat method able to effectively prevent the occurrence of condensation inside a chamber.
2. Description of the Related Art
In the process of production of a semiconductor device etc., a testing apparatus is necessary for testing the finally produced IC chip or other device. As one type of such a testing apparatus, there is known an apparatus for testing an IC chip at ordinary temperature or temperature conditions lower than ordinary temperature. This is because it is guaranteed as one of the features of an IC chip that it operates well at ordinary temperature or low temperature.
In such a testing apparatus, the top of the test head is covered by the chamber, the inside is made an air-tight space, IC chips are conveyed on the test head, the IC chips are pushed against the test head for connection, and the IC chips are tested while making the inside of the chamber an ordinary temperature within a certain temperature range or a low temperature state. This type of test is used to test the IC chips well and sort them into at least good chips and defective chips.
In this type of testing apparatus of the related art, in particular in low temperature tests, an abnormality sometimes occurs whereby it is no longer possible to maintain the temperature inside the chamber at a low temperature within a predetermined temperature range. When such a temperature abnormality occurs, the testing apparatuses of the related art were designed to output a temperature alarm signal.
When such a temperature alarm signal was emitted, the testing apparatuses of the related art were designed to stop all temperature control and notify the operator of the testing apparatus of the w abnormality. The operator then investigated the abnormality of the testing apparatus and requested suitable measures be taken.
When the operator fails to take suitable measures, when there is no operator nearby, etc., however, the testing apparatus remains in a state with the temperature control stopped and condensation is liable to occur inside the chamber. If condensation occurs inside the chamber, the moisture of the condensation deposits on the terminals of the test head side and terminals of the IC chips etc. and is liable to cause the phenomenon of short-circuiting and liable to have a detrimental effect on the testing apparatus and IC chips. Therefore, it is necessary to effectively prevent the occurrence of condensation inside the chamber.
Further, it is necessary to maintain the inside of the chamber at a predetermined temperature range not only in low temperature tests (for example, -55.0.degree. C. to 15.9.degree. C.), but also in ordinary temperature tests (for example, 16.0.degree. C. to 39.9.degree. C.). The inside of the chamber sometimes become a lower temperature in state than the outside of the chamber. In such a case, a temperature alarm is emitted and the temperature control of the testing apparatus is stopped. If this is allowed to continue unchecked, condensation is liable to occur inside the chamber in the same way as at the time of a low temperature test.
Further, when continuously operating the testing apparatus over a long period of time for a low temperature test, the introduction of outside air along with the insertion and removal of IC chips to and from the inside of the chamber etc. is liable to cause condensation inside the chamber due to the accumulation of moisture inside the chamber even if there is no temperature alarm.